Guides
Headlight guides
These articles explain the same limits as the calculators. They do not sell a kit and they do not certify a lamp.
Aiming headlights
Wall distance, drop, and why a phone estimate is not a shop procedure.
Read the guideCondensation in a lamp
Fog, vents, and what you can observe without a photometer.
Read the guideAftermarket lamps and US rules
Plain English, not legal advice, and not a VIN catalog.
Read the guideWhat LED vs halogen actually changes
Watts, heat, and optional lumens. No invented brightness factor.
Read the guide